CKAD Application Observability and Maintenance Practice Question
Which probe type is used to indicate that a container is ready to serve traffic and should be added to Service endpoints?
⚠ Common exam trap
The CKAD exam often tests the distinction between readiness and liveness probes, trapping candidates who confuse 'is the container alive?' with 'is the container ready to serve?'.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Readiness probe
A Readiness probe determines whether a container is ready to accept traffic. If the probe fails, the container is removed from all Service endpoints, ensuring only healthy pods receive requests. This is the correct probe for indicating readiness to serve traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Readiness probe
Why this is correct
Readiness probes are the mechanism Kubernetes uses to decide if a container is ready to serve traffic. When a readiness probe fails, the pod is removed from all backing Service endpoints, so no requests are forwarded to it, but the container is not killed or restarted. This makes readiness probes the direct indicator of whether a container is prepared to handle incoming traffic, including dependencies like database connectivity or loaded configuration.
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Liveness probe
Why it's wrong here
Liveness probes check whether the container is still running and functional; if they fail, the kubelet kills and restarts the container according to the restart policy. A container passing its liveness probe can still be unready, because liveness failures determine only whether the process should be recycled, not whether it should receive requests. Thus, a liveness probe is unrelated to the condition of being ready to serve traffic; it only confirms the container is alive.
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Startup probe
Why it's wrong here
Startup probes are used only to determine whether an application has finished starting up, commonly for containers with slow initialization times. As long as the startup probe fails, liveness and readiness probes are suspended, preventing premature restarts; once it succeeds, the other probes resume and the startup probe is no longer checked. This probe type does not directly affect Service endpoints, so it does not answer whether the container is ready to serve traffic—it merely gates the start of the other probe checks.
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Both liveness and readiness probes
Why it's wrong here
Choosing both liveness and readiness probes together is incorrect because they answer different questions: liveness governs restarts, while readiness governs traffic routing. A pod can be live but not ready, so liveness success does not contribute to joining Service endpoints; only the readiness probe's success determines whether traffic is sent. Therefore, even when both are configured, it is the readiness probe—not the combination—that indicates the container is ready to serve traffic.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKAD practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKAD exam.